The spliceosomal cyclophilin H is a specific component of the human U4/U6 small nuclear ribonucleoprotein particle, interacting with homologous sequences in the proteins U4/U6-60K and hPrp18 during pre-mRNA splicing. We determined the crystal structure of the complex comprising cyclophilin H and the cognate domain of U4/U6-60K. The 31 amino acid fragment of U4/U6-60K is bound to a region remote...

The U6 small nuclear RNA (snRNA) undergoes major conformational changes during the assembly of the spliceosome and catalysis of splicing. It associates with the specific protein Prp24p, and a set of seven LSm2p-8p proteins, to form the U6 small nuclear ribonucleoprotein (snRNP). These proteins have been proposed to act as RNA chaperones that stimulate pairing of U6 with U4 snRNA to form the int...

Cajal bodies (CBs) are subnuclear organelles of animal and plant cells. A role of CBs in the assembly and maturation of small nuclear ribonucleoproteins (snRNP) has been proposed but is poorly understood. Here we have addressed the question where U4/U6.U5 tri-snRNP assembly occurs in the nucleus. The U4/U6.U5 tri-snRNP is a central unit of the spliceosome and must be re-formed from its componen...

Prp3 is an essential U4/U6 di-snRNP-associated protein whose functions and molecular mechanisms in pre-mRNA splicing are presently poorly understood. We show by structural and biochemical analyses that Prp3 contains a bipartite U4/U6 di-snRNA-binding region comprising an expanded ferredoxin-like fold, which recognizes a 3'-overhang of U6 snRNA, and a preceding peptide, which binds U4/U6 stem II...

In this paper, the Fischer matrices of maximal subgroup G = 21+8+ : (U4(2):2) U6(2):2 will be derived from quotient group Q G/Z(21+8+) 28 (U4(2):2), where Z(21+8+) denotes center extra-special 2-group 21+8+. Using approach, and associated ordinary character table are computed in an elegantly simple manner. This approach can used to compute any split extension form 21+2n+ :G, n ∈ N, provided irr...

U4 RNA is one of several small nuclear RNAs involved in the splicing of mRNA precursors. The domestic chicken has two genes per haploid genome that are capable of encoding U4 RNA. The U4X RNA gene (which encodes a sequence variant of U4 RNA that was unknown prior to the cloning of the gene) and the U4B RNA gene were both expressed in vivo in each of seven adult and three embryonic chicken tissu...

Within the sequence motif conserved at the extreme ends of the influenza virus vRNAs, a unique natural variation, U or C, is observed at position 4 of the 3' end. To test the role of this nucleotide, two isogenic A/WSN/33 viruses, carrying either C4 or U4 nucleotide at the 3' end of the neuraminidase (NA) gene, were generated. Compared with the C4 virus, the U4 virus exhibited delayed synthesis...

The Sm proteins are loaded on snRNAs by the SMN complex, but how snRNP-specific proteins are assembled remains poorly characterized. U4 snRNP and box C/D snoRNPs have structural similarities. They both contain the 15.5K and proteins with NOP domains (PRP31 for U4, NOP56/58 for snoRNPs). Biogenesis of box C/D snoRNPs involves NUFIP and the HSP90/R2TP chaperone system and here, we explore the fun...